Question

Which among the following alkali metal chlorides crystallises in the form of a hydrate?

• A. LiCl
• B. KCl
• C. CsCl
• D. NaCl

Hint:

Among alkali metals, lithium compounds show maximum hydration due to the small size of \(\text{Li}^+\).

Answer 1

The Correct Option is A

Step 1: Hydration tendency of alkali metal ions.
Smaller cations have higher hydration energy and a stronger tendency to form hydrates.

Step 2: Analyse lithium ion.
\(\text{Li}^+\) has the smallest size among alkali metal ions and therefore has very high hydration energy.

Step 3: Behaviour of LiCl.
Due to strong hydration of \(\text{Li}^+\), lithium chloride readily forms hydrated crystals such as \(\text{LiCl}\cdot\text{H}_2\text{O}\).

Step 4: Conclusion.
Lithium chloride is the alkali metal chloride that crystallises in the hydrated form.